Remove redundant code to set the device on the LightningModule

[awaelchli]

What does this PR do?

This removes some lines that are no longer needed.
They were originally added in #12985, but then later we decided to set the device earlier in the Trainer: #18021. There are tests for this.

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📚 Documentation preview 📚: https://pytorch-lightning--19877.org.readthedocs.build/en/19877/

cc @Borda @justusschock @awaelchli

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-11, lightning, 3.8, 2.0, oldest)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 2.0)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 2.1)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 2.2)	success	✅
pl-cpu (macOS-14, lightning, 3.10, 2.3)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 2.0, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.0)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.2)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.3)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 2.0, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.0)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.2)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.3)	success	✅
pl-cpu (macOS-11, pytorch, 3.8, 2.0)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.8, 2.0)	success	✅
pl-cpu (windows-2022, pytorch, 3.8, 2.0)	success	✅
pl-cpu (macOS-12, pytorch, 3.11, 2.0)	success	✅
pl-cpu (macOS-12, pytorch, 3.11, 2.1)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.11, 2.0)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.11, 2.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.11, 2.0)	success	✅
pl-cpu (windows-2022, pytorch, 3.11, 2.1)	success	✅

These checks are required after the changes to src/lightning/pytorch/strategies/deepspeed.py, src/lightning/pytorch/strategies/fsdp.py.

🟢 pytorch_lightning: Azure GPU

Check ID	Status
pytorch-lightning (GPUs) (testing Lightning | latest)	success	✅
pytorch-lightning (GPUs) (testing PyTorch | latest)	success	✅

These checks are required after the changes to src/lightning/pytorch/strategies/deepspeed.py, src/lightning/pytorch/strategies/fsdp.py.

🟢 pytorch_lightning: Benchmarks

Check ID	Status
lightning.Benchmarks	success	✅

These checks are required after the changes to src/lightning/pytorch/strategies/deepspeed.py, src/lightning/pytorch/strategies/fsdp.py.

🟢 pytorch_lightning: Docs

Check ID	Status
docs-make (pytorch, doctest)	success	✅
docs-make (pytorch, html)	success	✅

These checks are required after the changes to src/lightning/pytorch/strategies/deepspeed.py, src/lightning/pytorch/strategies/fsdp.py.

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to src/lightning/pytorch/strategies/deepspeed.py, src/lightning/pytorch/strategies/fsdp.py.

🟢 install

Check ID	Status
install-pkg (ubuntu-22.04, app, 3.8)	success	✅
install-pkg (ubuntu-22.04, app, 3.11)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.8)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.11)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.8)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.11)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.8)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.11)	success	✅
install-pkg (ubuntu-22.04, notset, 3.8)	success	✅
install-pkg (ubuntu-22.04, notset, 3.11)	success	✅
install-pkg (macOS-12, app, 3.8)	success	✅
install-pkg (macOS-12, app, 3.11)	success	✅
install-pkg (macOS-12, fabric, 3.8)	success	✅
install-pkg (macOS-12, fabric, 3.11)	success	✅
install-pkg (macOS-12, pytorch, 3.8)	success	✅
install-pkg (macOS-12, pytorch, 3.11)	success	✅
install-pkg (macOS-12, lightning, 3.8)	success	✅
install-pkg (macOS-12, lightning, 3.11)	success	✅
install-pkg (macOS-12, notset, 3.8)	success	✅
install-pkg (macOS-12, notset, 3.11)	success	✅
install-pkg (windows-2022, app, 3.8)	success	✅
install-pkg (windows-2022, app, 3.11)	success	✅
install-pkg (windows-2022, fabric, 3.8)	success	✅
install-pkg (windows-2022, fabric, 3.11)	success	✅
install-pkg (windows-2022, pytorch, 3.8)	success	✅
install-pkg (windows-2022, pytorch, 3.11)	success	✅
install-pkg (windows-2022, lightning, 3.8)	success	✅
install-pkg (windows-2022, lightning, 3.11)	success	✅
install-pkg (windows-2022, notset, 3.8)	success	✅
install-pkg (windows-2022, notset, 3.11)	success	✅

These checks are required after the changes to src/lightning/pytorch/strategies/deepspeed.py, src/lightning/pytorch/strategies/fsdp.py.

---

Thank you for your contribution! 💜

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53%. Comparing base (32e2418) to head (3a2ef75).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #19877      +/-   ##
==========================================
- Coverage      84%      53%     -31%     
==========================================
  Files         426      418       -8     
  Lines       35237    35080     -157     
==========================================
- Hits        29505    18647   -10858     
- Misses       5732    16433   +10701